THE FOSSIL FERNS. 



181 



analogy to the ferns of the carboniferous period, which were 

 lofty trees, far surpassing in height and magnificence even 

 their tropical congeners of the present day. A splendid 

 specimen of alsophila brunoniana, placed on the staircase of 

 the British Museum, affords an idea of the arborescent 

 ferns of the tropics, which attain the height of forty or fifty 



FIG. 113. 

 Equisetum columnare. Br. PL 120. 



FIG. 114. 

 Calamites cannaeformis. Schlot. 



feet, their stems being marked with scars from the decay of 

 the leaf-stalks, and their summits crowned with a spreading 

 dome of graceful foliage. The scars resemble those of other 

 monocotyledonous plants, especially the palms, but differ in 

 the circumstance that in the ferns they are commonly lon- 

 gitudinal, while in the palms they are transverse. From 

 their number and variety, they afford some of the most in- 

 teresting fossil remains which the vegetable kingdom has 

 produced. Their leaves are elegant, and display great variety 

 of form and diversity of venation : from these characters the 

 generic and specific distinctions of the family are obtained. 

 They are often preserved in great perfection, and even the 

 organs of fructification are occasionally observable at the 

 back of the leaf. 



The fossil ferns are divided into the following genera, 

 determined by the character of their fronds : pachypteris, 

 sphenopteris , cyclopteris,glossopteris, neuropteris, odontopteris, 

 anomopteris, tceniopteris,pecopteris, lonchopteris, clathropteris, 

 schizopteris, otopteris, caulopteris, and sigillaria, fyc. ; the two 

 latter occurring only as stems ; the last being considered by 

 some recent inquirers as a dicotyledonous plant. 



